Hybrid vehicles equipped with engines and motors as driving sources are conventionally known. A hybrid vehicle is equipped with a power storage device such as a battery for storing electric power to be supplied to a motor. The battery is charged with electric power generated by a power generator driven by an engine and electric power regenerated using the motor during deceleration of the vehicle.
Such a hybrid vehicle can run using either one or both of an engine and a motor as a driving source, depending on an operation state of the vehicle. Therefore, for example, when the vehicle speed is low, the engine is stopped and only the motor can be used as a driving source for running.
In a running state in which the engine is stopped and only the motor is used as a driving source, no exhaust gas is emitted and therefore the impact on the environment is small. Therefore, it is desired to indicate the current operation state relative to the operation region in which the engine can be stopped, so that the state in which the engine is stopped can be maintained as long as possible.
Japanese Patent Laying-Open No. 2008-74321 (Patent Document 1) discloses an indicator apparatus for a hybrid vehicle that incorporates an internal combustion engine and an electric motor as motive power sources, and that is capable of traveling in one of traveling modes including a first mode where traveling is performed while the internal combustion engine is stopped and a second mode where traveling is performed while both of the internal combustion engine and the electric motor are operated. The indicator apparatus includes: a control portion switching between the traveling modes based on an output demand from a driver; a first indicator portion indicating a first state amount that changes in accordance with the output demand from the driver; and a second indicator portion indicating, as corresponded to the first state amount, a second state amount that shows switching of the traveling modes.
Japanese Patent Laying-Open No. 2008-74321 further discloses that when starting of the internal combustion engine is demanded based on a prescribed condition, the traveling mode is forcibly switched to the second mode, and the second state amount is changed so as to show that the second mode is selected for an entire range of the first state amount.
Japanese Patent Laying-Open No. 2008-74321 further discloses that when a switch for selecting traveling in the first mode is operated by the driver, a threshold value for switching the traveling modes is changed so that a range in which traveling is performed in the first mode is increased, and the second state amount is changed in accordance with the change of the threshold value for switching. The 106-th paragraph of Japanese Patent Laying-Open No. 2008-74321 describes that the traveling mode is switched to HV mode (second mode) and threshold value TH (second state amount) is returned to a normal value when the state of charge becomes not greater than a prescribed value.